The selection of materials for soft actuators is a critical step in their design. In this work, a methodology has been established to ensure that the selected material meets the required mechanical and thermal properties. This study focuses on Ecoflex 00-20, a soft silicone with high elasticity, excellent tear resistance, and an 845% elongation rate, making it ideal for flexible actuators. A basic pneumatic actuator was designed. It consists of a cylindrical elastomer-coated cavity that inflates upon air injection. A rigid sheet restricts lateral expansion, enabling controlled bending. The actuator’s mold was 3D-printed, and the curing process took 16 h. For kinematic characterization, an OptiTrack camera system was used to analyze actuator motion. Data from 20 tests (each lasting 30 s) were processed through polynomial smoothing techniques. The results revealed a hysteresis effect, attributed to the elastomer’s nonlinear behavior. A mathematical model was developed using Hooke’s Law, incorporating Young’s modulus and Poisson’s ratio to predict deformation. The findings confirm that Ecoflex 00-20-based actuators are promising for applications in soft robotics and rehabilitation, offering safe and precise movement for human interaction and prosthetic applications.